Hour Meter / Standard model TT2APack Size:1Oregon 42-447 Tiny Tach Digital Tach/Hour Meter, 5+ years lithium battery life, not replaceable, RPM display from 1 to 19,000, Unit potted to prevent damage from moisture and vibration, RPM update time 1/2 second, 6' cable length, RPM reading adjustable from 1 spark per 2 revolutions to 8 sparks per revolution, Works on most gasoline engines